Irawan Wijaya Kusuma

Inhibitory components from the buds of clove (Syzygium aromaticum) on melanin formation in B16 melanoma cells

In the course to find a new whitening agent, we evaluated the methanol extract from bud of clove (Syzygium aromaticum) on melanin formation in B16 melanoma cells. Eugenol and eugenol acetate were isolated as the active compounds and showed melanin inhibition of 60% and 40% in B16 melanoma cell with less cytotoxicity at the concentration of 100 and 200 μg/mL, respectively. Furthermore, an essential oil prepared from the bud of clove, which contain eugenol and eugenol acetate as dominant components, showed melanin inhibition of 50% and 80% in B16 melanoma cells at the concentration of 100 and 200 μg/mL, respectively.

Biological Activity and Phytochemical Analysis of Three Indonesian Medicinal Plants, Murraya koenigii, Syzygium polyanthum and Zingiber purpurea

Extracts of Indonesian medicinal plants, Murraya koenigii, Syzygium polyanthum, and Zingiber purpurea were investigated for their biological activity. The presence of phytochemicals, cytotoxicity, and antimicrobial and antioxidant activities were investigated. Parts of M. koenigii, S. polyanthum, and Z. purpurea were extracted with ethanol. The extracts were evaluated for antimicrobial activity using the disc diffusion method, while antioxidant activity was determined with a 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. Cytotoxicity was investigated using the brine shrimp lethality test, and phytochemical screening was performed using a standard method. M. koenigii leaf extract exhibited the most activity in the test microorganism activity index (AI), 0.38-1.25, when compared with standard drugs. S. polyanthum ripened fruit displayed significant antioxidant activity (90%) in comparison to ascorbic acid (95%). Z. purpurea rhizome extract possessed the highest cytotoxic effect with a LC(50) of 52 μg/mL. Phytochemical analysis revealed that carbohydrate, tannin, alkaloid, steroid, triterpenoid, and flavonoid were present in the extracts of M. koenigii leaves and twigs, S. polyanthum leaves and ripened and unripe fruits, and Z. purpurea rhizome, while saponin was only present in the S. polyanthum ripened fruit extract. Our work revealed that the M. koenigii leaves, S. polyanthum ripened fruit, and Z. purpurea rhizome extracts have potential as sources of new antimicrobial, antioxidant, and cytotoxic compounds, respectively.

Screening of Indonesian plants for tyrosinase inhibitory activity

In our efforts to find new tyrosinase inhibitory materials, we investigated 44 Indonesian plants belonging to 24 families for tyrosinase inhibitory activity. The extracts of 5 Artocarpus woods showed potent tyrosinase inhibitory activity (over 80% at 100 µg/ml) similar to a positive control, kojic acid. In Artocarpus woods, the extracts of the sapwoods showed stronger inhibitory activity than those of the heartwoods. Chlorophorin was isolated as one of the active compounds in the sapwood of Artocarpus heterophyllus. The content of chlorophorin in sapwood was higher than that in heartwood.

Cytotoxic effect of artocarpin on T47D cells

In our screening projects for anticancer agents from natural resources, artocarpin [6-(3-methyl-1-butenyl)-5,2′,4′-trihydroxy-3-isoprenyl-7-methoxyflavone] isolated from wood of jack fruit (Artocarpus heterophyllus) showed potent cytotoxic activity on human T47D breast cancer cells. The mode of action of artocarpin was evaluated by its effect on cell viability, nuclear morphology, cell cycle progression, expression of protein markers for apoptosis, and mitochondrial membrane potential (Δψm). These results showed that artocarpin caused a reduction of cell viability in a concentration-dependent manner and an alteration of cell and nuclear morphology. Moreover, the percentage of the sub-G1 phase formation was elevated dose-dependently. Artocarpin induced activation of caspase 8 and 10 as indicated by stronger signal intensity of cleaved-caspase 8 and weaker signal intensity of caspase 10 markers detected after artocarpin treatment. In addition, we also noticed the activation of caspase 3 by artocarpin. There were negligible changes in mitochondrial membrane potential (Δψm) due to artocarpin treatment. All together, these data indicated that artocarpin induced apoptosis in T47D cells possibly via an extrinsic pathway.

Tyrosinase inhibitory effect of quercetin 4′-O-β-D-glucopyranoside from dried skin of red onion (Allium cepa)

In an effort to find a new whitening agent, we focused our attention on Allium cepa (red onion). Based on biologically guided fractionation using mushroom tyrosinase, quercetin 4′-O-β-D-glucopyranoside was isolated from the dried skin of A. cepa. Quercetin 4′-O-β-D-glucopyranoside showed tyrosinase inhibitory activity using L-tyrosine or L-DOPA as a substrate, with IC50 values of 4.3 and 52.7 µM, respectively. Based on the results obtained, the dried skin of red onion possesses ingredients with potential for skin-whitening cosmetics with anti-tyrosinase activity.

Antioxidant Activity and Cytotoxicity of the Traditional Indonesian Medicine Tahongai (Kleinhovia hospita L.) Extract

We investigated the leaves of Kleinhovia hospita, a plant which has been traditionally used in Indonesia as phytotherapy to cure liver disease, to describe antioxidant materials from plant sources. K. hospita leaves were extracted with methanol and further partitioned into n-hexane, diethyl ether, and ethyl acetate. The antioxidant activity of each fraction and the residue was assessed using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method and their cytotoxicity on HepG2 liver cancer cells was determined by a MTT assay. The K. hospita leaf methanol extract showed strong antioxidant activity (96%) compared with vitamin C (98%) by the DPPH method and the measured activity from the subsequent extracts of the methanol extract were 48.9% for n-hexane, 74.0% for diethyl ether, 84.3% for ethyl acetate, and 77.1% for the residue. The MTT assay showed the cytotoxicity of the methanol extract on HepG2 cells at 14%, 76%, and 80% at concentrations of 50 microg/mL, 87.5 microg/mL, and 125 microg/mL, respectively. Leaf extracts of the medicinal plant K. hospita showed potent antioxidant activity and moderate cytotoxicity on HepG2 liver cancer cells.

Validation of Eupatorium triplinerve Vahl Leaves, a Skin Care Herb from East Kalimantan, Using a Melanin Biosynthesis Assay

In searching for a new material made from natural resources that could be used as a whitening agent, we focused on the plants used for skin treatment by the native people of East Kalimantan. The methanol extract of the leaves of Eupatorium triplinerve Vahl showed antimelanogenesis activity in a melanin biosynthesis assay. By activity-guided fractionation, 7-methoxycoumarin (1) was isolated as an active compound. The IC50 of 1 on mushroom tyrosinase was 2360 μM (L-tyrosine was used as the substrate) and above 2840 μM (L-DOPA was used as the substrate), respectively. Regarding melanin formation inhibition in B16 melanoma cells, the IC50 of 1 was 1780 μM with 83% cell viability at IC50. Based on these results, we validated that the leaf extract is in line with the traditional use of the Dayak tribe in East Kalimantan.

A new 4-arylflavan from the pericarps of Horsfieldia motleyi displaying dual inhibition against α-glucosidase and free radicals

Abstract In search for effective antidiabetic agents that simultaneously inhibit α-glucosidase and scavenge free radicals, Horsfieldia motleyi showed promising bioactivity according to the proposed criteria. Bioassay-guided isolation of pericarp extract yielded a new 4-arylflavan named myristinin G (6), whose gross structure and absolute configuration were verified by 2D NMR and electronic circular dichorism (ECD). Myristinin G (6) concomitantly inhibited α-glucosidases (IC50 107.0 and 126.9 μM) and free radicals (SC50 54.3 and 279.9 μM). Of interest, 6 inhibited sucrase through an uncompetitive manner, which is rare in nature.

Antagonistic activity of extra cellular product and component bacteria of Pseudomonas sp. against Aeromonas hydrophila from tilapia aquaculture in East Borneo

This research aims to evaluate the antibacterial activity of 103 protein fractions obtained from the extra cellular product (ECP) and four different fractions from the cellular component (whole cell product, heat-killed whole cell product, intra-cellular product and crude extra cellular product) of Pseudomonas sp. against Aeromonas hydrophila pathogen on tilapia fish. Antibacterial activities were measured by the zone of inhibition in a sensitivity test against A. hydrophila. Intra-cellular product, whole cell product, and heat-killed whole cell product of Pseudomonas sp. exhibited inhibition zone of 10 mm and crude of fraction ECP showed inhibition zone of 11 mm. All protein fractions of ECP displayed potential activity against A. hydrophila in Nila tilapia. 73.8% protein fractions had resistant inhibition and 20.4% possessed intermediate inhibition. 5.8% fractions caused sensitive inhibition. Our results showed that protein fractions of ECP were found to be the most effective to inhibit A. hydrophila gr...

Anticandidal activity of several plants used by Bentian tribe in East Kalimantan, Indonesia

Research on the potential of diversity, ethnobotany and ethnopharmacology and bioactivity of plants used by local tribes in Kalimantan is still relatively inadequate. This research aimed to evaluate the antimicrobial activity of medicinal plants used by the Bentian tribe in East Kalimantan. In this study, we used 19 medicinal plants collected from our previous study. From these samples, we tested 21 extracts derived from n-hexane, ethyl acetate and ethanol as representative of different polarity solvents. The Anticandidal activity was examined using agar well diffusion against Candida albicans. Anticandidal activity of the extracts was evaluated by relative comparison with the standard antibiotic, chloramphenicol. The results showed that among the n-hexane extracts, those derived from Blumea balsamifera and Triumfettar homboidea exhibited the highest inhibition activity on the growth of C. albicans by 27-56%. The ethyl acetate extract of B. balsamifera and Stachytarpheta jamaicensis observed to have the h...